Pedal driven bicycles have been well known in the art of man powered vehicles. The most common pedal system uses a chain driven pair of sprockets to which pedals are attached to the front drive sprocket while a chain is attached to the front drive sprocket and the rear wheel sprocket propelling the rear wheel to provide movement. This system has the pair of pedals positioned 180 degrees relative to the other, so in combination, they rotate 360 degrees about the axis of rotation of the drive sprocket; with the rider exerting maximum force on each downward motion on each pedal. This is a most simple and efficient way to move a two wheeled bicycle.
A more complicated, but arguably superior drive system for a bicycle or scooter has been developed utilizing a four bar link drive mechanism. The drive mechanism employs a drive sprocket attached to a bottom bracket fixed onto a bicycle or scooter frame, a crank link attached to the drive sprocket or the axle of the drive sprocket and rotationally fixed to the rotation of the drive sprocket, a coupling link attached at one end to the crank link and at an opposite end to a foot pedal, the foot pedals being pivotally attached at one end to the crank link and at an opposite end, the foot pedal is pivotally attached at an end, called the proximal hinge location of the vehicle frame forming a four bar linkage assembly wherein the distances between axis of rotations at the various attachment locations define the movement. The distance between axis of the pedal proximal hinge location attachment to the frame and the axis of the drive sprocket forms a virtual frame link F. The distance between the axis of the proximal hinge location of the pedal to the axis of the coupling link to pedal attachment defines a dimension P, the distance between pair of axis of the coupling link defines a dimension C2 and the dimension between the pair of axis of the crank link defines a dimension C1. The combination of dimensions F, P, C1 and C2 define the four bar linkage and are critical to the performance of the foot pedals and the vehicle. This drive mechanism as described provides a reciprocating pedal action wherein the rider can exert downward pressure on each downward pedal stroke to propel the vehicle. The foot pedals are set so when one pedal is at the bottom of its stroke, the other pedal is approximately at its maximum stroke relative to the other so that the rider can provide alternating propulsion strokes with each leg.
This drive mechanism is described in greater detail in U.S. patent application Ser. Nos. 12/554,366 filed on Sep. 4, 2009 entitled “Pedal-Drive System for Manually Propelling Multi Wheeled Cycles” and 12/848,567 filed on Aug. 2, 2010 entitled “Improved Scooter and Pedal Drive Assembly; the entirety of each application being incorporated herein by reference.
The present invention does not claim this four bar linkage drive system, but rather teaches and discloses a unique simulator device capable of providing optimal solutions to the physical location and dimensions of the four bar linkage system.
During the development of a reciprocating pedal drive system it was discovered that the positioning of the components on a vehicle frame such as a scooter or bicycle were critical. The dimensions and relative locations of F, P, C1 and C2 affected how the foot pedals moved. Minor adjustments of one element affected the entire pedal performance. Selection of these dimensions was such that minor variations in manufacturing tolerances during assembly could result in poor pedal action.
These problems were not simply poor pedal operation, but included a linkage lock up preventing pedal movement or even pedal reversal causing the linkages to change or reverse direction. The present invention describes a device to enable quick and reliable establishment of these critical dimensions.